Polymers exhibit many advantageous properties such as low mass density, chemical stability, high strength-to-mass ratio and the like. Polymeric materials typically have a low thermal conductivity and polymeric substances such as foams prepared from amorphous polymers are widely used for thermal insulation. Materials for heat exchangers and thermal management, however, require high thermal conductivity which is commonly associated with conductors known in the art such as copper, aluminum, titanium and the like.
Recent reports of high thermal conductivity in polyethylene nano fibers and natural biopolymers have renewed the researchers' interest in thermally conductive polymers. It is known that polymers with high crystallinity and chain alignment tend to have higher thermal conductivities. Heat in the polymer is conducted in the direction of the covalently bonded molecular chains and in case of oriented products, the conductivity depends on the crystallinity, orientation, crystal size, length of molecular chains, chemical bridge points, crystal or amorphous boundary, defects, ends and entanglements of the molecular chains and morphologies composed of crystal and amorphous. The randomly oriented crystal region composed of folded ultrahigh molecular weight polyethylene (UHMWPE) chains changes to highly oriented crystal region composed of extended chains. Heat conduction of the extended chains in the direction of the covalent-bonded chain axis in the crystal regions contributes to the high thermal conductivity.
Conventional preparations of UHMWPE fibers for preparing tapes or sheets of UHMWPE involve the steps of preparing gel where large quantities of suitable solvents are used to disentangle the polymer chains so as to achieve highly oriented crystal region composed of extended chains. Furthermore, the processes reported so far are highly energy intensive and cumbersome, thus limiting their use in commercial applications.
The present disclosure therefore envisages a process for preparing highly conductive UHMWPE that mitigates the drawbacks associated with the conventional processes.